Shutdown complete (mysqld 8.0.40-31) Percona Server (GPL), Release '31', Revision '49317865'.

Good afternoon my friends,
I’m Brazilian so sorry for my not very good English.

Today I installed percona on my ubuntu 20 to migrate mysql 5.7.42 to sql google cloud however when installing percona I had the misfortune of no longer having access to mysql, from what I understand in the logs ubuntu is trying to use mysql 8.0 which It was installed with percona, I need to return it to normal as it was before, below I include some system logs:

sudo apt-cache policy mysql-server
mysql-server:
Installed: 5.7.42-1ubuntu18.04
Candidate: 5.7.42-1ubuntu18.04
Version table:
8.0.40-0ubuntu0.20.04.1 500
500 Index of /ubuntu focal-updates/main amd64 Packages
500 Index of /ubuntu focal-security/main amd64 Packages
8.0.19-0ubuntu5 500
500 Index of /ubuntu focal/main amd64 Packages
*** 5.7.42-1ubuntu18.04 1001
500 Index of /232905/apt/ubuntu bionic/mysql-5.7 amd64 Packages
100 /var/lib/dpkg/status
N: Ignoring file ‘mysql-apt-config_0.8.10-1_all.deb’ in directory ‘/etc/apt/sources.list.d/’ as it has an invalid filename extension

Are you trying to install Percona Server for MySQL and MySQL Community version together on the same host?
Here is how you should install Percona Server for MySQL